APPLICATIONS INFORMATION
Figure 1 shows the basic connections required for operation
of the INA134. Decoupling capacitors are strongly recom-
mended in applications with noisy or high impedance power
supplies. The capacitors should be placed close to the device
pins as shown in Figure 1. All circuitry is completely
independent in the dual version assuring lowest crosstalk
and normal behavior when one amplifier is overdriven or
short-circuited.
As shown in Figure 1, the differential input signal is con-
nected to pins 2 and 3. The source impedances connected to
the inputs must be nearly equal to assure good common-
mode rejection. A 10Ω mismatch in source impedance will
degrade the common-mode rejection of a typical device to
approximately 74dB. If the source has a known impedance
mismatch, an additional resistor in series with the opposite
input can be used to preserve good common-mode rejection.
Do not interchange pins 1 and 3 or pins 2 and 5, even though
nominal resistor values are equal. These resistors are laser
trimmed for precise resistor ratios to achieve accurate gain
and highest CMR. Interchanging these pins would not pro-
vide specified performance.
AUDIO PERFORMANCE
The INA134 and INA2134 were designed for enhanced ac
performance. Very low distortion, low noise, and wide band-
width provide superior performance in high quality audio
applications. Laser-trimmed matched resistors provide opti-
mum common-mode rejection (typically 90dB), especially
when compared to circuits implemented with an op amp and
discrete precision resistors. In addition, high slew rate
(14V/µs) and fast settling time (3µs to 0.01%) ensure good
dynamic performance.
The INA134 and INA2134 have excellent distortion charac-
teristics. THD+Noise is below 0.002% throughout the audio
frequency range. Up to approximately 10kHz distortion is
below the measurement limit of commonly used test equip-
ment. Furthermore, distortion remains relatively flat over its
wide output voltage swing range (approximately 1.7V from
either supply).
OFFSET VOLTAGE TRIM
The INA134 and INA2134 are laser trimmed for low offset
voltage and drift. Most applications require no external offset
adjustment. Figure 2 shows an optional circuit for trimming
the output offset voltage. The output is referred to the output
reference terminal (pin 1), which is normally grounded. A
voltage applied to the Ref terminal will be summed with the
output signal. This can be used to null offset voltage as
shown in Figure 2. The source impedance of a signal applied
to the Ref terminal should be less than 10Ω to maintain good
common-mode rejection.
V
2
2
V–
1µF
4
INA134
–In
V
2
R
1
25kΩ
R
2
25kΩ
V+
1µF
7
2
5
6
V
OUT
= V
3
– V
2
+In
3
V
3
R
3
25kΩ
R
4
25kΩ
1
FIGURE 1. Precision Difference Amplifier (Basic Power
Supply and Signal Connections).
INA134
R
1
R
2
5
6
V
O
10Ω
V
3
3
R
3
R
4
+15V
V
O
= V
3
– V
2
Offset Adjustment
Range = ±300µV
1
499kΩ
100kΩ
10Ω
–15V
FIGURE 2. Offset Adjustment.
®
INA134/2134
8
BURR-BROWN [ BURR-BROWN CORPORATION ]
